Guidelines for Evaluating Superheavy Load Routes

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E.G. Fernando

Publication Date:

October 1997


Superheavy loads are defined as loads that have gross vehicle weights in excess of 1112 kN. In the past, loads in excess of 8900 kN have been moved. Before a permit can be issued for a Superheavy load move, TxDOT needs to determine whether the proposed route is structurally adequate to sustain the Superheavy load. The analysis of damage potential under Superheavy loads concerns the likelihood of a rapid, load-induced shear failure as opposed to the long-term accumulation of permanent deformation and fatigue due to repeated load applications. A methodology for evaluating Superheavy load routes was developed in Project 0-1335, Movement of Superheavy Loads Over the State Highway System. This methodology is now implemented in TxDOT for permitting Superheavy load moves. It is based on an incremental, non-linear layered elastic pavement model for predicting the induced pavement response under surface wheel loads. Predicted stresses under a Superheavy load are used with the Mohr-Coulomb yield criterion to evaluate the potential for pavement damage prior to the Superheavy load move. Since the initial development, a follow-up study led to enhancements in the analysis procedure. Researchers developed routines to evaluate the edge load condition and to determine the failure wheel load for a given pavement structure. The former modification is used to evaluate the potential for edge shear failure on moves where the wheel loads will travel close to the edge of a given pavement with unpaved shoulders. The latter modification is used in identifying alternative trailer configurations to prevent pavement damage during Superheavy load moves. This project summary report provides guidelines in the application of the methodology to evaluate Superheavy load routes.

Report Number:



Superheavy Loads, Pavement Evaluation, Pavement Response Modeling, Non-linear Material Behavior, Mohr-Coulomb Yield Criterion

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